Vertical lathes are tools which are generally designed for the machining parts which, due to their dimensions and weight, would make the fixing thereof in a horizontal lathe difficult. They usually comprise a vertical shaft and a rotating chuck. The rotating chuck is assembled on a base and between both there are arranged bearings allowing the rotation between the rotating chuck and the base. The part to be machined is secured on the base whereas the machining tool or tools (lathe, milling tools, etc.) are assembled in one or several columns. A bearing is arranged between the base and the rotating chuck which enables the rotation of the chuck with respect to the base.
The use of hydrostatic tracks as bearings is known, which hydrostatic tracks are made up of a series of arched elements in the form of circle segments arranged such that they form a circumference, and which comprise housings into which there is injected pressurised hydraulic oil filling the housings. If the pressure of the hydraulic oil is maintained, such hydraulic oil overflows and lifts the rotating chuck with respect to the base. A film of oil acting as a sliding track is thus formed between both elements. Given that the rotating chuck must have the possibility of rotating at a determined speed for the machining, and given that the machining force of the tool on the part must be supported by the rotating chuck, the latter is subjected to a highly considerable torque generated by the applying of force of the tool at a distance with respect to the rotation shaft of the chuck. This torque varies considerably depending on the dimensions of the part to be machined. Therefore, for a determined size of the part to be machined, there is a suitable chuck diameter and a suitable hydrostatic track, essentially the diameter of the hydrostatic track is fixed for a determined size of the part. This results in the drawback that a hydrostatic track of a different size and, therefore, a different vertical lathe or machine are needed for each size of the part to be machined, which involves a serious limitation in relation to the versatility of use, and, therefore, the cost of vertical lathes equipped with such hydrostatic tracks.